<9. Advanced Engineering >
● Example Applications of inter-FCN/FCJ Communication
Two example applications using inter-FCN/FCJ communication are briefly described
below.
- Data sharing by multiple tasks on duplex CPU configuration
In an FCN-500 configured with duplex CPUs, if global variables are shared by
multiple tasks, data identity on the control and standby CPUs cannot be
guaranteed.
This program can be resolved using, inter-FCN-500 communication to the FCN-
500 itself.
As inter-FCN/FCJ communication is executed during the CPUs’ idle time, the
received data is updated at the beginning of the task on both the control and
standby CPUs.
This guarantees identity of the control and standby CPUs and enables sharing of
global variables.
Specifically, specify a its own IP adress for inter-FCN communication. This
establishes a connection from an FCN-500 to itself for inter-FCN communication.
As the two IP addresses are identical so that automatic assignment of client and
server roles by comparison of IP addresses cannot be done, specify one of the
inter-FCN communication applications explicitly as a client, and the other as a
server.
- Checking the status of remote FCN-500, FCN-RTU using confirmed
communication
As described earlier, confirmed communication allows the source FCN-500 or
FCN-RTU to receive responses for READ/WRITE requests from a destination
FCN-500 or FCN-RTU, as well as to detect communication errors if no response
is received.
Communication errors may be due to communication interruption caused by
CPU load increase of the destination FCN-500 or FCN-RTU, CPU module
failure, or communication interruption caused by failure of communication
equipment or cables.
Using confirmed communication, an FCN-500 or FCN-RTU can detect whether
there is a communication error and thus determine whether the destination FCN-
500 or FCN-RTU is normal.
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